/*
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * The Original Code is Copyright (C) 2018 Blender Foundation.
 * All rights reserved.
 *
 * Contributor(s): Sergey Sharybin.
 *
 * ***** END GPL LICENSE BLOCK *****
 */

/** \file blender/blenlib/intern/BLI_linklist_lockfree.c
 *  \ingroup bli
 */

#include "MEM_guardedalloc.h"

#include "BLI_linklist_lockfree.h"
#include "BLI_strict_flags.h"

#include "atomic_ops.h"

void BLI_linklist_lockfree_init(LockfreeLinkList *list)
{
	list->dummy_node.next = NULL;
	list->head = list->tail = &list->dummy_node;
}

void BLI_linklist_lockfree_free(LockfreeLinkList *list,
                                LockfreeeLinkNodeFreeFP free_func)
{
	if (free_func != NULL) {
		/* NOTE: We start from a first user-added node. */
		LockfreeLinkNode *node = list->head->next;
		while (node != NULL) {
			LockfreeLinkNode *node_next = node->next;
			free_func(node);
			node = node_next;
		}
	}
}

void BLI_linklist_lockfree_clear(LockfreeLinkList *list,
                                 LockfreeeLinkNodeFreeFP free_func)
{
	BLI_linklist_lockfree_free(list, free_func);
	BLI_linklist_lockfree_init(list);
}

void BLI_linklist_lockfree_insert(LockfreeLinkList *list,
                                  LockfreeLinkNode *node)
{
	/* Based on:
	 *
	 *   John D. Valois
	 *   Implementing Lock-Free Queues
	 *
	 *   http://people.csail.mit.edu/bushl2/rpi/portfolio/lockfree-grape/documents/lock-free-linked-lists.pdf
	 */
	bool keep_working;
	LockfreeLinkNode *tail_node;
	node->next = NULL;
	do {
		tail_node = list->tail;
		keep_working =
			(atomic_cas_ptr((void **)&tail_node->next, NULL, node) != NULL);
		if (keep_working) {
			atomic_cas_ptr((void **)&list->tail, tail_node, tail_node->next);
		}
	} while (keep_working);
	atomic_cas_ptr((void **)&list->tail, tail_node, node);
}

LockfreeLinkNode *BLI_linklist_lockfree_begin(LockfreeLinkList *list)
{
	return list->head->next;
}
